Investigation of temperature effect on thermo-mechanical property of carbon fiber/PEEK composites

Considering the temperature sensitivity and two-phase incompatibility of the fiber matrix interface, carbon fiber-reinforced thermoplastic composites suffer from weak interfacial bonding strength. To investigate the delamination damage and shear failure mechanism of T700/PEEK composites at varying temperatures, interfacial shear strength (IFSS) and interlaminar shear strength (ILSS) were performed by employing micro debonding experiments and three-point bending. The results indicated that at temperatures below the glass transition, the IFSS of T700/PEEK composites was positively correlated with temperature, and the average strength recorded was 52 ± 6 MPa. When the glass transition temperature was exceeded, the bonding state between polyether ether ketone material and fiber surface became tighter, resulting in a slight increase in IFSS, reaching 60 ± 4 MPa. Further, the ILSS of T700/PEEK composites was tested, and the results indicated a negative correlation between ILSS and temperature, with a maximum ILSS of 40 ± 2 MPa observed at 23°C, and a minimum of 11 ± 1 MPa recorded at 230°C. The decline in bending strength observed with increasing temperature was attributed to the separation of the fiber and matrix interface at high temperatures, which reduced the mechanical properties of T700/PEEK composites. By conducting temperature related mechanical performance tests on T700/PEEK composite materials, the obtained test results will help researchers expand the application scenarios of this material, deepen the relationship between the temperature and its performance, and thus more quickly explore the mechanism of temperature action.